Gen1 Active Tunable SiGe Integrated Parallel Synthesis Filters (PSF) without Q-Enhancement

This paper presents a proof of concept of high-order LC tunable filters without Q-enhancement in a SiGe BiCMOS process using a parallel synthesis approach. By manipulating the parallel resonators phase properties, a 4
^th
-order band-pass filter is synthesized using subtraction of the two LC-resonators. Despite the on-chip low-Q passives, a wide center-frequency tuning, a large 3-dB tunable bandwidth, and high out-of-band attenuation is achieved. The presented filter is center-frequency tunable from 7 to 11 GHz with a constant 3-dB bandwidth of 1.5 GHz. Additionally, the filter bandwidth can also be tuned from 850 MHz to 1800 MHz. The proposed filter offers a competitive performance, typically suitable for RF receive chain after a low-noise amplifier, in terms of in-band IIP3 of -2 to +3 dBm, NF of 11 to 12 dB, fixed power consumption of 33.6 mW, a highly integrated small form factor, frequency and bandwidth tunability, all without the need for any positive feedback Q-enhancement circuit. Other features of the proposed filter are switched-varactor controls for high linearity, on-chip passive baluns, continuous tuning offering a high number of filter states to the system, simple control, and compatibility with existing digital controller. The proposed filter is implemented in Tower Semiconductor 180 nm SiGe BiCMOS process to achieve higher integration of phased-arrays common receive module at Northrop Grumman Mission Systems and further enables imaging radar, EW and SIGINT systems tunability.